1. Field of the Invention
The present invention relates to a semiconductor laser and a method of manufacturing the same, and more particularly to a semiconductor laser which is easy to manufacture and a method of manufacturing the same.
2. Description of the Prior Art
Conventionally, a technique has been proposed to improve the luminous efficiency of radiation of a semiconductor laser. Such a technique is disclosed, for example, in Japanese Laid-Open Utility Model Publication No. 2-92961.
FIG. 12 shows a sectional structure of such a prior art semiconductor laser. In FIG. 12, a semiconductor laser chip 80 is formed by stacking in sequence an n-GaAs substrate 82, an n-Al.sub.0.35 Ga.sub.0.65 As clad layer 83, an undoped GaAs active layer 84, a p-Al.sub.0.35 Ga.sub.0.65 As clad layer 85 and a p-GaAs contact layer 86. An n-side electrode 81 is attached to the n-GaAs substrate 82, and a p-side electrode 87 is attached to the p-GaAs contact layer 86. An insulating protector coat 91 is attached to a radiant end surface 92 of the semiconductor laser chip 80. The insulating protector coat 91 has a projecting convex lens 91a formed at a portion opposite the end of the active layer 84. With this construction, a laser beam emitted from the end of the active layer 84 can be converged by the projecting convex lens 91a. Thus, the luminous efficiency of radiation can be substantially improved.
In the above prior art, however, the active layer 84 is not located in the central portion of the semiconductor laser chip 80 in the stacking direction thereof. Instead, it is located in the vicinity of the p-side electrode 87. As seen in FIG. 12, the height of the semiconductor laser chip 80 in the stacking direction includes a height de of 2 to 20 .mu.m and another height ds of 100 to 200 .mu.m. Therefore, it has been impossible for the projecting convex lens 91a formed by resin dropping to have its optical axis positioned at the end of the active layer. Furthermore, design for a converging lens and others in an external optical system has been complicated.